Someday, we'll be able to predict the onset of a major earthquake with the same relative accuracy as weather forecasts -- not perfect, but definitely useful days or sometimes a week or more in advance. Someday, but not today.

But what we do have today is a growing body of knowledge around what happens prior to a quake. Quite often, it's another quake -- a small foreshock to something much larger, or even a tremor on another fault line. With this in mind, the US Geological Survey has opened up a "Real Time Forecast" map for California earthquakes. The forecasts only look out 24 hours, a short but still better-than-nothing warning.

The forecast is generated by combining two types of information. First, a 'background' assessment is made of earthquake risk around California, by assessing the physical properties of various geological sites, along with the statistical behaviour of fault lines over long periods of time.Added to this are the anticipated knock-on effects of any seismological activity that has occurred over the previous days, months or years. This is what causes day-to-day percentages to change. This week, for example, a magnitude-4.7 aftershock in the Parkfield area, where a medium-sized quake occurred last September, has caused probabilities in the region to jump to around 1%.

The quake forecast map is something of a proof-of-concept for now. While it would be good to see similar maps for other parts of the world, I suspect they need to work out the idea's utility a bit more. The percentages are generally quite low, sufficiently so to make the map unlikely to impinge on people's day-to-day awareness. Still, I'd like to see a daily RSS feed, or maybe one which only sends out a new map if a forecast goes above a certain percentage.

We're likely to see more of these sorts of maps and displays in the coming years, as we learn more about how geophysical systems work, and (with regards to weather phenomena) as global warming triggers greater climate uncertainty.

"Someday, we'll be able to predict the onset of a major earthquake with the same relative accuracy as weather forecasts"

So, sometimes accurate, sometimes dead wrong? I'm only writing what everyone's thinking; you schedule your outdoor wedding by weather probability and have it ruined by weather reality. Only now picture your wedding with false evacuations, or the price of being wrong hundreds or thousands dead (no different from today, of course)...

I would argue that this is not a particularly useful application of this technology; in a seismically active region, the chances of an earthquake occuring at any given moment are between 0-100%. It is an inherently unpredictable event, with unpredictable effects. I suppose if we developed technology that alerted us to electromagnetic signals that some animals seem to feel (if that is indeed what they are sensing), such a map would be useful, but even then, what kind of earthquake will it be?
In the meantime, I would wish this were put to better use, like the above posts mention.

Wow, sorry, kind of started ranting...

BTW, Tyler, the Spanish flu epidemic killed an enormous number of young and healthy people - no one knows why they were also targeted. Maybe you better distribute that map to everyone.

Posted by: justus on 24 May 05

As a professional geologist, I have worked on earthquake prediction now for more than a quarter of a century and found an accurate method to predict larger earthquakes not only as to probable dates (to within a couple of days or so), but also as to most probable times (to within an hour or so) in any particular location. But some "unseen forces" (be it hackers or espionage organizations) keep blocking the progress of my research. To all you good guys in this deceitful world - HELP!!!